Edited:

I just bought a '99 Dodge Ram quad cab 4x4 with the 5.9L, auto. This truck is in MINT condition inside and out and only has 29.5k miles on it. The problem is that it only gets 8.2mpg when pulling my boat (it's only 18')!! It gets about 14mpg on the highway with my tailgate out. Not only does it get terrible mpg, but it has no power. I mean it takes everything it's got just to pull my ski boat. My little 4x4 V6 ranger pulled it better than this thing.

I put in a K&N and it didn't help at all. I need help! This thing is killing me in gas! There are no weird noises in the engine and everything works as it should! Is it exhaust or what? It also seems to run a lot better when the engine is cold? After driving for about 15 minutes and the engine is warmed up, it seems to get worse.

I know you don't get the best gas mileage with a 4x4 because i've had them all! But 8.2 pulling a small boat is un real!

Thanks for the help!

 

Your 14 mpg on the highway doesnt suprise me, I got a 98' with a 360 and it gets the same on the highway with a tonnuea cover(however you spell it). 8 mpg with a boat, that seems a little low, but if you are towing up hill or in a hilly place, and you let the revs go high then it wouldn't suprise me. But it does seem a little on the low side.

I tow a 18.5' Searay, I never checked my gas mileage when towing yet but when I get a chance to I can tell you.(I don't tow for long distances, only to the ramp and back to the summer house, 3 miles round trip.

Are you pumping the right gas? Are you sure you are doing your calculations right? Maybe you need a tune up also, check your maintence records(if you got them all) to see the last time it was done.

But that might be right 8mpg because the highway mpg seem to be right with what I get.

Thats my 2

Mike.

 

I get about 12 mpg all around, whether I'm cruising in O.D., in stop and go traffic, or hauling a huge load with it taken out of O.D.

Mine seems fine, plenty of power when towing, and I have 33" tires with stock gearing. When I first got the truck it was a gutless wonder, which was because at 54,000 miles, it still had the factory plugs, wires, cap, and rotor. I suggest replacing those first, as Mikeg1005 said, and see what that does. If that helps, good, if not, I'd look into the exhaust, maybe the cat is plugged up

 

Iam in the same boat here. I havent towed anything yet, but gas mileage is around 13-14 mpg no matter where I drive. Like you said, it seems to have more power when the engine is cold, but that has to do with a richer mixture in warm up mode, it also runs in "open loop" for the first few minutes/miles of driving.
Does your truck accelerate in "steps" when you step on it from a standstill? A dog below but pulling like crazy when passing 3000 rpm?
I think yours and mine truck fel victim to the infamous "death Flash" whre the dealer secretly removed the original program and replaced it with a detuned program, saving the engine form detonation damage. I am going to install an aftermarket program either from Hypertech, KenneBell or Superchips to get rid of this reflash. I have driven an early 98 with a 360 and it was night and day difference in performance. It pulled a 2000 lbs trailer at 75 mph up a 8 % grade in 3rd gear locked. It was able to spin the tires too. I cant get em to spinn even when it rains.

 

"Death Flash"? I've never heard of that. Did the dealsers really do that? My Ram probably doesn't have that, because it does ping a little while accelerating in OD unless I run 89 or 93 octane in it.

 

I run 87 octane, and pull a landscape trailer. I also have 33's with the stock 3:55 gear, and it lights up the tires whenever I ask it to. It pulls the trailer with my lawn mowing equipment like its not even there.

 

i can burn my 35's posi all day too .....
my truck is somewhat doggish, im going to invest in a fastman TB.